Anyone knows what's this? My son's teacher just told me he suddenly developed this rash all over. What's the cause of it and recommended remedies? Thanks!

Yeaup agree with the other mommies. Looks pretty much like hives. I get hives whenever I get too stressed and those reddish bumps look a lot like the hives I get. It will go away in a few hours or a day. If it gets too unbearable, I slather on some aloe vera gel. Once, I went to the doctor to get a shot because it got really bad.